Positive photoresist composition, coating film thereof, and novolac phenol resin

Abstract

A positive photoresist composition includes 3 to 80 parts by mass of a novolac phenol resin (B) relative to 100 parts by mass of a cresol novolac resin (A). The novolac phenol resin (B) has a repeating structural unit represented by formula (1) [In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms and X represents a structure (x1) represented by formula (2)

The invention claimed is: 
     
       1. A positive photoresist composition comprising 3 to 80 parts by mass of a novolac phenol resin (B) relative to 100 parts by mass of a cresol novolac resin (A), wherein the novolac phenol resin (B) has a repeating structural unit represented by formula (1) below: 
       
         
           
           
               
               
           
         
         [In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms and X represents a structure (x1) represented by formula (2) below: 
       
       
         
           
           
               
               
           
         
         (In the formula, R 1 , R 2 , and R 3  each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; m and n each independently represent an integer of 1 to 4; p represents an integer of 0 to 4; and t represents 1 or 2) or an aromatic hydrocarbon group (x2) other than the structure (x1)], 
         wherein a content of the structure (x1) relative to the total number of the structure (x1) and the structure (x2) is 85% or more. 
       
     
     
       2. The positive photoresist composition according to  claim 1 , wherein the structural unit represented by formula (1) is a structural unit represented by formula (1-1) below: 
       
         
           
           
               
               
           
         
         (In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms and R 1  and R 2  each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms). 
       
     
     
       3. The positive photoresist composition according to  claim 2 , wherein a weight-average molecular weight of the novolac phenol resin (B) is 5,000 to 35,000. 
     
     
       4. The positive photoresist composition according to  claim 3 , wherein the novolac phenol resin (B) contains 90% or more of (x1) relative to a total of 100 of (x1) and (x2). 
     
     
       5. A coating film obtained by applying and drying the positive photoresist composition according to  claim 3 . 
     
     
       6. The positive photoresist composition according to  claim 2 , wherein the novolac phenol resin (B) is obtained by performing polycondensation of 2,5-xylenol and 4-hydroxybenzaldehyde in the presence of an acid catalyst to obtain a polycondensate represented by formula (2-1) below: 
       
         
           
           
               
               
           
         
         and then allowing the polycondensate to react with an aldehyde compound (D) in the presence of an acid catalyst. 
       
     
     
       7. The positive photoresist composition according to  claim 6 , wherein the aldehyde compound (D) is formaldehyde. 
     
     
       8. The positive photoresist composition according to  claim 2 , wherein the novolac phenol resin (B) contains 90% or more of (x1) relative to a total of 100 of (x1) and (x2). 
     
     
       9. A coating film obtained by applying and drying the positive photoresist composition according to  claim 2 . 
     
     
       10. The positive photoresist composition according to  claim 1 , wherein the structural unit represented by formula (1) is a structural unit represented by formula (1-2) below: 
       
         
           
           
               
               
           
         
         (In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms and R 1  and R 2  each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms). 
       
     
     
       11. The positive photoresist composition according to  claim 10 , wherein a weight-average molecular weight of the novolac phenol resin (B) is 1000 to 5000. 
     
     
       12. The positive photoresist composition according to  claim 10 , wherein the novolac phenol resin (B) is obtained by performing polycondensation of 2,6-xylenol and 4-hydroxybenzaldehyde in the presence of an acid catalyst to obtain a polycondensate represented by formula (2-2) below: 
       
         
           
           
               
               
           
         
         and then allowing the polycondensate to react with an aldehyde compound (D) in the presence of an acid catalyst. 
       
     
     
       13. The positive photoresist composition according to  claim 12 , wherein the aldehyde compound (D) is formaldehyde. 
     
     
       14. The positive photoresist composition according to  claim 10 , wherein the novolac phenol resin (B) contains 90% or more of (x1) relative to a total of 100 of (x1) and (x2). 
     
     
       15. The positive photoresist composition according to  claim 1 , wherein the novolac phenol resin (B) contains 90% or more of (x1) relative to a total of 100 of (x1) and (x2). 
     
     
       16. The positive photoresist composition according to  claim 1 , comprising 20 to 60 parts by mass of the novolac phenol resin (B) relative to 100 parts by mass of the cresol novolac resin (A). 
     
     
       17. The positive photoresist composition according to  claim 1 , wherein the cresol novolac resin (A) is prepared by using, as essential raw materials, m-cresol or p-cresol, and formaldehyde. 
     
     
       18. A coating film obtained by applying and drying the positive photoresist composition according to  claim 1 . 
     
     
       19. A novolac phenol resin comprising a repeating structural unit represented by formula (1) below: 
       
         
           
           
               
               
           
         
         [In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms and X represents a structure (x1) represented by formula (2) below: 
       
       
         
           
           
               
               
           
         
         (In the formula, R 1 , R 2 , and R 3  each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; m and n each independently represent an integer of 1 to 4; p represents an integer of 0 to 4; and t represents 1 or 2) or an aromatic hydrocarbon group (x2) other than the structure (x1)], 
         wherein a content of the structure (x1) relative to the total number of the structure (x1) and the structure (x2) is 85% or more, and the structural unit represented by formula (1) is a structural unit represented by formula (1-1) below: 
       
       
         
           
           
               
               
           
         
         (In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms and R 1  and R 2  each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms). 
       
     
     
       20. A novolac phenol resin comprising a repeating structural unit represented by formula (1) below: 
       
         
           
           
               
               
           
         
         [In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms and X represents a structure (x1) represented by formula (2) below: 
       
       
         
           
           
               
               
           
         
         (In the formula, R 1 , R 2 , and R 3  each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; m and n each independently represent an integer of 1 to 4; p represents an integer of 0 to 4; and t represents 1 or 2) or an aromatic hydrocarbon group (x2) other than the structure (x1)], 
         wherein a content of the structure (x1) relative to the total number of the structure (x1) and the structure (x2) is 85% or more, and the structural unit represented by formula (1) is a structural unit represented by formula (I-2) below: 
       
       
         
           
           
               
               
           
         
         (In the formula, R represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms and R 1  and R 2  each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms).